Maine's wild blueberry growers are monitoring their fields for a harmful new fruit fly that arrived in the U.S. five years ago and poses a threat to the state's crop.

With the blueberry harvest set to kick into gear later this week, growers have been watching out for the tiny spotted wing drosophila. The fly is a native of Asia that caught some growers off guard when it first appeared in Maine's blueberry fields last summer.

This year's harvest is projected to be about average at 86 million pounds or so. That's down from last year's harvest of 91 million pounds, the second-largest crop on record.

Wild blueberries are native to North America, and Maine and Canada are the only places that grow them for commercial sale.